A coder is fed with precoded data such that the absolute value of the running digital sum (RDS) of the code words as produced by the coder is limited. This is achieved by ensuring that in a group of 2 code words, the RDS of the first code word is compensated by the RDS of the second code word. The RDS at the end of the second code word is then zero and the excursions of the RDS from the start of the first code word until the end of the second code word are limited because there are only a limited number of bits that can contribute to an increase of the absolute value of the RDS.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for coding a stream of input words using a channel code, the method comprising the acts of: precoding the stream of input words into a stream of precoded input words; and coding the stream of precoded input words into a stream of groups of N code words such that a combined running digital sum of each predefined group of N adjacent code words equals zero.
2. The method as claimed in claim 1 , wherein N equals 2.
3. The method as claimed in claim 1 , wherein after the step of coding the stream of precoded input words into a stream of groups of N code words the method comprises the step of storing the groups of N code words using a groove position modulation on a storage medium.
4. The method as claimed in claim 1 , wherein coding the precoded stream of input words is achieved using a parity preserving coder.
5. The method as claimed in claim 4 , wherein the parity preserving coder is a 17PP coder.
6. The method as claimed in claim 5 , wherein the stream of input words is precoded using the following table: In Out 00 1010 01 0001 10 0111 11 0101 1010 00001000.
7. The method as claimed in claim 6 , wherein before the act of storing the groups of N code words in using the groove position modulation on the storage medium remaining DC components are removed using a high-pass filter.
8. The method as claimed in claim 5 , wherein the stream of input words is precoded using the following table: In Out 00 -> 10 10 10 -> 00 01 11 -> 01 11 01 -> 01 01 11 11 -> 00 00 10 00.
9. The method as claimed in claim 1 , wherein coding the precoded stream of input words is achieved using a parity inverting coder.
10. An apparatus for storing data on a recording medium comprising an encoder which arranged for coding the stream of precoded input words into a stream of groups of N code words and comprising a precoder for coding the stream of input words into a stream of precoded input words such that a combined running digital sum of each predefined group of N adjacent code words equals zero.
11. The apparatus as claimed in claim 10 , wherein N equals 2.
12. The apparatus as claimed in claim 10 , wherein the apparatus is arranged for storing the groups of N code words using a groove position modulation on a storage medium.
13. The apparatus as claimed in claim 10 , wherein the encoder is a parity preserving coder.
14. The apparatus as claimed in claim 13 , wherein the parity preserving coder is a 17PP coder.
15. The apparatus as claimed in claim 14 , wherein the precoder is operative to precode the stream of input words using the following table: In Out 00 1010 01 0001 10 0111 11 0101 1010 00001000.
16. The apparatus as claimed in claim 15 , wherein the apparatus is operative to remove remaining DC components using a high-pass filter before storing the groups of N code words using the groove position modulation on the storage medium.
17. The apparatus as claimed in claim 14 , wherein the precoder is operative to precode the stream of input words using the following table: In Out 00 -> 10 10 10 -> 00 01 11 -> 01 11 01 -> 01 01 11 11 -> 00 00 10 00.
18. The apparatus as claimed in claim 10 , wherein the encoder is a parity inverting coder.
19. A record carrier comprising a stream of input words stored as a stream of groups of N code words such that a combined running digital sum of each predefined group of N adjacent code words equals zero.
20. The record carrier as claimed in claim 19 , wherein N=2.
21. The record carrier as claimed in claim 19 , wherein the groups of N code words are stored using a groove position modulation.
22. The record carrier as claimed in claim 19 , wherein the stream of input words is precoded using the following table: In Out 00 1010 01 0001 10 0111 11 0101 1010 00001000.
23. The record carrier as claimed in claim 19 , wherein the stream of input words is precoded to form precoded words using the following table: In Out 00 1010 10 0001 11 0111 01 0101 1111 00001000; wherein “In” represents the stream of input words and “Out” represents the precoded words.
24. A method for decoding a stream of N code words into a stream of N output words, wherein the stream of M output words is postcoded to form postcoded words using the following table: In Out 1010 00 0001 01 0111 10 0101 11 00001000 1010; wherein “In” represents the stream of M output words and “Out” represents the postcoded words.
25. A method for decoding a stream of N code words into a stream of M output words, wherein the stream of M output words is postcoded to form postcoded words using the following table: In Out 1010 00 0001 10 0111 11 0101 01 00001000 1111; wherein “In” represents the stream of M output words and “Out” represents the postcoded words.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
June 17, 2003
May 15, 2007
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.